# 🐳 How to Install and Use Docker on Ubuntu 22.04

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A step-by-step guide to installing Docker Community Edition (CE) on Ubuntu 22.04, based on the [DigitalOcean Tutorial](https://www.digitalocean.com/community/tutorials/how-to-install-and-use-docker-on-ubuntu-22-04).

---

## 📋 Table of Contents
- [Prerequisites](#-prerequisites)
- [Installation Guide](#-installation-guide)
  - [Step 1: Update Packages](#1-update-packages)
  - [Step 2: Install Dependencies](#2-install-dependencies)
  - [Step 3: Add Docker Repository](#3-add-docker-repository)
  - [Step 4: Install Docker Engine](#4-install-docker-engine)
- [Post-Installation Configuration](#-post-installation-configuration)
- [Verification](#-verification)

---

## 🛠 Prerequisites

Before you begin, ensure you have:
* One **Ubuntu 22.04** server.
* A user with `sudo` privileges.
* An active firewall (optional but recommended).

---

## 🚀 Installation Guide

### 1. Update Packages
First, update your existing list of packages to ensure you are getting the latest versions.

```bash
sudo apt update
```
### 2. Install Dependencies
Install the prerequisite packages that allow apt to use packages over HTTPS.
```Bash
sudo apt install apt-transport-https ca-certificates curl software-properties-common
```
### 3. Add Docker Repository
Add the GPG key for the official Docker repository to your system to ensure downloads are valid.
```Bash
curl -fsSL [https://download.docker.com/linux/ubuntu/gpg](https://download.docker.com/linux/ubuntu/gpg) | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
```
Add the Docker repository to your APT sources.
```Bash
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] [https://download.docker.com/linux/ubuntu](https://download.docker.com/linux/ubuntu) $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
```
### 4. Install Docker Engine
Update the package database again with the Docker packages from the newly added repo.
```Bash
sudo apt update
```
Finally, install Docker.

```
sudo apt install docker-ce
```
### ⚙ Post-Installation Configuration
Run Docker Without Sudo (Optional)
By default, the docker command can only be run by the root user or by a user in the docker group. To avoid typing sudo for every command, add your current user to the docker group.

Add your user to the docker group:

```Bash
sudo usermod -aG docker ${USER}
```
Apply the new group membership (requires logging out or running the following):
```Bash
su - ${USER}
```
Verify that your user is added to the group:
```Bash
groups
```
Output should look like: sammy sudo docker

### ✅ Verification
Check that Docker is running correctly.

```Bash
sudo systemctl status docker
```
To verify that you can pull images from Docker Hub, run the "Hello World" container:
```bash
docker run hello-world
```

If successful, you will see a message indicating that your installation appears to be working correctly.

### 📚 Resources
Official Docker Documentation
DigitalOcean Docker Tutorial